Field
Embodiments of the disclosure relate generally to the field of damping of dynamic resonance in aerospace structures and more particularly to a tuned mass damper (TMD) employing a voice coil/magnet combination as both an actuator and a lossy element for measuring and adjusting the TMD and structural response in an aerospace structure to which the TMD is attached and then adjusting the lossy element to self-tune the TMD for maximum reduction in dynamic response of the aerospace structure and TMD combination.
Background
Tuned mass dampers (TMDs) are heavily damped resonant devices which add damping to lightly damped vibrational modes of a structure by dynamically coupling into the lightly damped modes. In practice, a TMD is a damped spring/mass resonator that is tuned so that its frequency is close to a lightly damped mode on the host structure. The TMD is attached to the host structure at a location of large amplitude motion for the mode in question and its motion is coupled into the host structure's motion. If the TMD is tuned correctly, two damped vibrational modes result, which take the place of the original lightly damped mode of the host structure and heavily damped mode of the TMD. Since aerospace structures tend to respond unfavorably at lightly damped modes in the presence of a dynamic disturbance environment, introduction of one or several TMDs can greatly reduce the dynamic response of a structure by damping problematic modes.
One of the challenges associated with installation of TMDs is tuning. Tuning involves the determination of the correct values of uncoupled natural frequency and damping for the device that yields the best performance in the coupled device. Finite element models are helpful in predicting the host structure dynamics, which can then be used to determine the frequency, damping and mass of the TMD that gives the best performance, but the finite element model has to be very accurate to be useful. Measured mode shapes of the structure without TMDs can also be used to determine the frequency, damping and mass of the TMD that gives the best performance. A typical installation involves using a finite element model to determine the moving mass in the TMD and the range of damping and frequencies required. Experimental data is then used to “tune” the frequency, damping and mass to the values that cause the biggest response reduction in host structure response. This process is often tedious and requires several iterations.
It is therefore desirable to provide a self-tuning TMD to eliminate the tuning step, save time and result in better overall performance for damping to reduce the dynamic response of a structure by damping problematic modes.